About 100 great white sharks visit Foveaux Strait each year between December and June to feed off the large local fur seal breeding colony. Over the past few years, new businesses had developed in which tourists are out in viewing cages off boats.

"The concern of the divers is that the use of burley and feeding to attract the sharks to the viewing cages will change the behaviour of the great whites to expect food around boats - putting divers at greater risk.

"There is also concern from wildlife experts that the sharks are being encouraged with the use of bait to attack the cage, causing permanent injury to the sharks," he said.

Tourism operators interacting with wildlife needed to be cautious of changing the behaviour of wildlife, which was why the Department of Conservation (DoC) regulated boats viewing dolphins, whales and seals.

"DoC will be writing to the shark cage tourism operators notifying them of the requirement to have a permit under the Wildlife Act," Dr Smith said.

"The issue over great white sharks is causing tension within the small Stewart Island community, between those supporting the tourism operators and those concerned about the risk to divers and others from shark attacks."

There were also reports of people deliberately killing the great whites even though they were a protected species, he said.

"The solution lies in tightening the rules around shark tourism operators and taking a firm approach against anybody deliberately killing these sharks."